This quick start gets developers integrating Meld crypto for the first time from zero to a working test transaction in under 30 minutes. Pick the Widget path for a no-code launch, or the White-Label API path if you plan to build your own UI.

Sandbox base URL: https://api-sb.meld.io — production credentials and URLs are separate. All examples below assume sandbox.

🚀 Choose your path

Perfect for: Fast launch, minimal development effort

What you get: Ready-made UI, instant crypto functionality
What you do: Get public-key URL → use directly → redirect users
Development required: None

➡️ Jump to Widget Quick Start

White-Label API — 30 minutes

Perfect for: Custom UI, complete design control

What you get: API endpoints for quotes, transactions, webhooks
What you do: Build custom UI → API integration → launch provider widgets
Development required: API integration, custom UI

➡️ Jump to White-Label Quick Start

Time required: 5 minutes Difficulty: No coding required

Before you begin

A Meld dashboard invitation (check your email; if missing contact your account manager)
Access to the Meld dashboard’s Developer tab

Step 1: Get your public-key URL

The Meld Dashboard provides a complete, ready-to-use Widget URL.

Check your email for the Meld dashboard invitation
Click the invitation link and log in
In the dashboard, navigate to the Developer tab
Find Public Crypto Widget Key — this is your complete URL
Copy and save your Public Key URL securely

You get a complete URL from the dashboard, not just a key. This URL is ready to use immediately.

Append optional query parameters to pre-fill or lock fields:

https://meldcrypto.com/?publicKey=your_public_key&sourceAmount=100&destinationCurrencyCode=BTC&countryCode=US

See the URL Parameters Guide for all available parameters and the Customization Guide for styling options.

Integration examples

HTML link:

<a href="https://meldcrypto.com/?publicKey=your_public_key" target="_blank">
  Buy Crypto
</a>

JavaScript redirect:

function buyCrypto() {
  window.location.href = 'https://meldcrypto.com/?publicKey=your_public_key';
}

Step 3: Test your integration

Use your sandbox Widget URL (from the Developer tab in the sandbox environment)
Open the URL in your browser
Complete a test transaction using the test credentials
Verify the result in the dashboard — check the Transactions tab

If your transaction does not appear, open the Status dropdown on the Transactions tab and select Select All to include in-progress statuses.

Step 4: Go live

Use your production Widget URL (from the Developer tab in the production environment)
Test with a small real transaction
Start directing users to your widget

✅ Widget integration complete. Users can now buy crypto directly through your application. ➡️ Meld Checkout Customization Guide — styling and advanced options

White-Label API Quick Start

Time required: ~30 minutes Difficulty: API knowledge required

Before you begin

A Meld dashboard invitation (check your email)
Access to the Developer → API Keys section of the dashboard
A publicly reachable URL if you want to receive webhooks (optional; you can also poll the API)

Step 1: Get your API key

Your API key is required for all Meld API calls.

Check your email for the Meld dashboard invitation
Click the invitation link and log in
In the dashboard, navigate to Developer → API Keys
Click Reveal Key
Copy and save your API key securely

Always prefix your API key with BASIC in the Authorization header.Example: Authorization: BASIC W9kZTT7332okCEc1A9aqAq:3sYKoXQv6oHVHSts7G2agw9vTCXz

Step 2: Set up webhooks (optional)

Webhooks notify your server when transactions are created and updated. You can complete this step later and poll the API instead.

Requirements

A publicly accessible URL (localhost will not work)
For testing, consider ngrok, webhook.site or similar services

Setup

Navigate to Developer → Webhooks in the dashboard
Click Add Endpoint
Enter your webhook URL (must start with http or https)
Give your webhook a descriptive name
Select Subscribe to all events
Click Add endpoint

You will receive notifications to this URL for all transaction creations and updates.

Step 3: Test your API connection

Verify your API key by requesting a price quote.

Endpoint: POST /payments/crypto/quote
Authorization: BASIC [your-api-key]

Request

{
  "countryCode": "US",
  "sourceCurrencyCode": "USD",
  "destinationCurrencyCode": "BTC",
  "paymentMethodType": "CREDIT_DEBIT_CARD",
  "sourceAmount": 100
}

Example response

{
  "quotes": [
    {
      "serviceProvider": "TRANSAK",
      "sourceAmount": 100,
      "sourceCurrencyCode": "USD",
      "destinationAmount": 0.00163,
      "destinationCurrencyCode": "BTC",
      "exchangeRate": 61349.69,
      "totalFee": 3.45
    }
  ]
}

Testing options

Use Meld’s Postman collection
Use the interactive docs in your dashboard

Expected result

✅ 200 OK with quote details. If you receive 401 Unauthorized, recheck the BASIC prefix and your key.

Step 4: Create a test transaction

Create a test transaction without using real money.

Endpoint: POST /crypto/session/widget
Authorization: BASIC [your-api-key]

Request

{
  "countryCode": "US",
  "sourceCurrencyCode": "USD",
  "destinationCurrencyCode": "BTC",
  "paymentMethodType": "CREDIT_DEBIT_CARD",
  "sourceAmount": 100,
  "serviceProvider": "TRANSAK",
  "walletAddress": "bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh"
}

Example response

{
  "id": "ses_01HEXAMPLEID",
  "widgetUrl": "https://global-stg.transak.com/?apiKey=...&sessionId=...",
  "token": "eyJhbGciOi..."
}

Replace walletAddress with your own test wallet or use the example above.

Complete the test flow

Copy the widgetUrl from the API response
Open the URL in your browser
For KYC testing, use any fake SSN and any image for the ID upload
For payment testing, use card 4111 1111 1111 1111, any future expiry, and any 3-digit CVV

📚 Full test data reference: Sandbox testing credentials

Step 5: Verify your transaction

Option A — Using webhooks

Check your webhook endpoint for the transaction notification
Extract the transactionId from the webhook payload
Call GET /payments/transactions/{transactionId} to retrieve the full record

Option B — Without webhooks

Call GET /payments/transactions to return your recent transactions
Locate your transactionId and read its current status

Dashboard verification

Navigate to the Transactions tab
If your transaction isn’t visible, click the Status dropdown and select Select All

✅ White-Label API integration complete. You can now build custom crypto experiences. ➡️ Build Custom UI Guide — complete implementation guide

Troubleshooting

🚫 401 Unauthorized

Ensure BASIC is prefixed before your API key
Check for extra spaces or incorrect formatting

🚫 Webhook not received

Verify URL is publicly accessible
Check firewall settings
Ensure the webhook endpoint returns a 2xx status code

🚫 Transaction not visible

Change the status filter to Select All in the dashboard
Wait 30 seconds and refresh
Confirm you are looking at the correct environment (sandbox vs production)

For a full list of transaction states and what each one means, see Transaction Statuses.

Quick Start

🚀 Choose your path

Widget Integration — 5 minutes

White-Label API — 30 minutes

Widget Integration Quick Start

Before you begin

Step 1: Get your public-key URL

Step 2: Use your Widget URL

Integration examples

Step 3: Test your integration

Step 4: Go live

White-Label API Quick Start

Before you begin

Step 1: Get your API key

Step 2: Set up webhooks (optional)

Requirements

Setup

Step 3: Test your API connection

Request

Example response

Testing options

Expected result

Step 4: Create a test transaction

Request

Example response

Complete the test flow

Step 5: Verify your transaction

Option A — Using webhooks

Option B — Without webhooks

Dashboard verification

Troubleshooting

🚫 401 Unauthorized

🚫 Webhook not received

🚫 Transaction not visible

​🚀 Choose your path

​Widget Integration — 5 minutes

​White-Label API — 30 minutes

​Widget Integration Quick Start

​Before you begin

​Step 1: Get your public-key URL

​Step 2: Use your Widget URL

​Integration examples

​Step 3: Test your integration

​Step 4: Go live

​White-Label API Quick Start

​Before you begin

​Step 1: Get your API key

​Step 2: Set up webhooks (optional)

​Requirements

​Setup

​Step 3: Test your API connection

​Request

​Example response

​Testing options

​Expected result

​Step 4: Create a test transaction

​Request

​Example response

​Complete the test flow

​Step 5: Verify your transaction

​Option A — Using webhooks

​Option B — Without webhooks

​Dashboard verification

​Troubleshooting

​🚫 401 Unauthorized

​🚫 Webhook not received

​🚫 Transaction not visible

🚀 Choose your path

Widget Integration — 5 minutes

White-Label API — 30 minutes

Widget Integration Quick Start

Before you begin

Step 1: Get your public-key URL

Step 2: Use your Widget URL

Integration examples

Step 3: Test your integration

Step 4: Go live

White-Label API Quick Start

Before you begin

Step 1: Get your API key

Step 2: Set up webhooks (optional)

Requirements

Setup

Step 3: Test your API connection

Request

Example response

Testing options

Expected result

Step 4: Create a test transaction

Request

Example response

Complete the test flow

Step 5: Verify your transaction

Option A — Using webhooks

Option B — Without webhooks

Dashboard verification

Troubleshooting

🚫 401 Unauthorized

🚫 Webhook not received

🚫 Transaction not visible